Never shut down the computer. Surriously, there isn't much point in shutting down; sleep works just as good. You should leave it on overnight every so often so that OS X can do it's maintenance._________________Computer Engineer
Junior, Brown University
15" NC8430 HP Laptop
1.42Ghz PPC Mac Mini, 1Gb RAM, 1st Gen
40GB G4 iPod
2GB Black iPod Nano

Well, it sounds to me like you have a memory leak in one of your Widgets. I believe that the AddressBook widget had a memory leak; either way, one of the preinstalled ones did, I think. You should try to download new ones or clear your dashboard and then restart and then add widgets waiting a couple hours afterwards and see if your Mini slows down. If it doesn't, keep adding widgets until it does. Once it does, you'll know which one is your memory leak.